An active transtensional fault system across the NE margin of the Tibetan Plateau and its influence on surrounding blocks

This is the authors' abstract. We don't add key points for this paper.

The newly discovered Tianzhu transtensional fault system cuts across the WNW-trending Qilian Shan orogen and thrust and strike-slip fault systems on the northeastern margin of the Tibetan Plateau. Using high-resolution satellite images, geomorphic mapping, trenching, and radiocarbon and optically stimulated luminescence dating, we found that the Tianzhu transtensional fault system consists of the Western Tianzhu Basin, Jinqianghe, Xuanmahe, Eastern Gulang, and Haxi faults, exhibiting active oblique normal faulting during the late Quaternary. The Tianzhu transtensional fault system experiences at least normal and left-lateral slip rates of 1.0 ± 0.2 mm/yr and 3.1 ± 0.2 mm/yr, respectively, and it is capable of producing earthquakes of Mw 7.2 or higher. The deformation patterns and mechanisms of large earthquakes differ on both sides of the fault system. It is believed that the Tianzhu transtensional fault system plays an important role in accommodating differential deformation of the NE Tibetan Plateau. Undergoing long-term tectonic processes, different parts of the NE Tibetan Plateau exhibit varying crustal motion, resulting in oblique shear and formation of the Tianzhu transtensional fault system. Combining analyses of fault distribution, seismic activity, and deep geophysical fields, the Tianzhu transtensional fault system and the Bayanwulashan and Langshan range-front faults in the northeast are likely to constitute a regionally evolving transtensional fault system, weakening the stability of the Gobi-Alashan block. Our results challenge the conventional understanding of continuous deformation along the Qilian-Haiyuan fault zone, provide new insights into the extension patterns of the NE Tibetan Plateau and its influence on the surrounding blocks, and inform our understanding of the types of transfer faults that cut through collisional orogens around the world.